| 1. |
- Mazur, Mikael, 1990, et al.
(författare)
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Field Trial of FPGA-Based Real-Time Sensing Transceiver over 524km of Live Aerial Fiber
- 2023
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Ingår i: Optical Fiber Communication Conference, OFC 2023. - 9781957171180
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Konferensbidrag (refereegranskat)abstract
- We perform fiber sensing over a 524 km live network using a real-time coherent transceiver prototype. Polarization and length changes from the link consisting exclusively of aerial fiber wound around high-voltage power cables are continuously monitored.
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| 2. |
- Mazur, Mikael, 1990, et al.
(författare)
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Real-Time Monitoring of Cable Break in a Live Network using a Coherent Transceiver Prototype
- 2024
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Ingår i: Optical Fiber Communication Conference, OFC 2024. - 9781957171326
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Konferensbidrag (refereegranskat)abstract
- We monitor a 524-km live network link using an real-time FPGA-based sensing-capable transceiver prototype during a human-caused cable break. Polarization sensing data shows minute-level potential break warning precursors, offering outage mitigation prospects.
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| 3. |
- Chen, Zexin, et al.
(författare)
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Transmitter optimization for PS-QAM signal in high spectral efficiency metro-transmission
- 2023
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 41, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Probabilistic constellation shaping (PCS) brings unprecedented flexibility to future optical networks. However, PCS combined with higher-order modulation formats and higher symbol rates puts more demands on the transmitter. For metro-transmission with high spectral efficiency (SE), transmitter impairments are responsible for a major portion of the system constraints. To address this issue, in this work we study the impact of transmitter impairments on probabilistically shaped quadrature amplitude modulation (PS-QAM) signals. First, we investigate the impact of transmitter impairments and radio frequency (RF) amplifier noise on the optimum shaping factor and the modulation depth within a fiber link. Then, we explore how generalized mutual information (GMI) and the shaping factor are affected by the noise from the transmitter. Next, we first jointly optimize the arcsine swing and the clipping ratio, in order to mitigate the transmitter impairments for the PS-QAM signal, when the modulation depth, the noise from the transmitter, the noise from the fiber optical channel, and the shaping factor are fixed. Then, we verify its validity for various configurations of transmission system. The optimized parameters primarily depend on the noise from the transmitter and turn out to be insensitive to the noise from the fiber optical link and the shaping factor. Finally, we experimentally verify the optimization strategy with PS-256QAM in back-to-back (B2B) transmission.
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| 4. |
- Deriushkina, Ekaterina, 1992, et al.
(författare)
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Characterisation of a Coupled-Core Fiber Using Dual-Comb Swept-Wavelength Interferometry
- 2021
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Ingår i: 2021 European Conference on Optical Communication, ECOC 2021.
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Konferensbidrag (refereegranskat)abstract
- We present a measurement of the transfer matrix of a coupled three-core fiber using a novel combination of swept-wavelength interferometry and dual-comb spectroscopy capable of measuring 1 THz bandwidth with a frequency resolution of 50 kHz with only a 25 GHz laser sweep.
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| 5. |
- Deriushkina, Ekaterina, 1992, et al.
(författare)
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Dual-Comb Swept-Wavelength Interferometry : Theory and Experiment
- 2022
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 0733-8724 .- 1558-2213. ; 40:19, s. 6508-6516
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Tidskriftsartikel (refereegranskat)abstract
- Much efforts have been put to elaborate and improve different high precision measurement schemes for characterization of advanced photonic devices and optical fibers with increasing bandwidth requirements. In light of this, swept-wavelength interferometry and dual-comb spectroscopy have been extensively applied in characterization procedures. In this paper we present in detail an experimental scheme that combines these two techniques and overcomes their limitations by using a tunable laser source in order to sweep over the frequency comb spacing and capture all intermediate frequencies. We demonstrate full-field broadband measurements over 1.25 THz comb bandwidth with increased frequency resolution, which can be performed in only 5 ms sweep. We also show that the nonlinearity of the laser sweep can be removed without an auxiliary interferometer in the setup.
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| 6. |
- Deriushkina, Ekaterina, 1992, et al.
(författare)
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Dynamic Model for Coupled-Core Fibers
- 2024
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Capacity trends in fiber optical communication systems are closely related to space-division multiplexing (SDM) solutions. A coupled-core fiber (CCF) is one of the most promising SDM candidates for a high data rate transmission because of its tolerance to nonlinear effects and reduced accumulation of group delay spread (GDS) with distance. As the modes of the cores in CCFs are strongly coupled, a communication link requires multiple-input multiple-output (MIMO) processing to recover the input signals. MIMO algorithms, in turn, operate with the different number of finite impulse response taps that represents the memory length of an equalizing filter. The calculation of the number of taps requires the knowledge of GDS, which can be estimated from the received data if a channel model is given. Moreover, if the model accounts for dynamic (time varying) effects it can be used to test the adaptive performance of MIMO equalizer. In this work we propose a straightforward dynamic random coupling model for CCFs. We investigate the dynamic behavior of group delays and impulse responses and also derive and analyze frequency and time autocorrelation functions.
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| 7. |
- Deriushkina, Ekaterina, 1992, et al.
(författare)
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Modeling of 3-Coupled-Core Fiber: Comparison Between Scalar and Vector Random Coupling Models
- 2024
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 42:2, s. 793-801
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Tidskriftsartikel (refereegranskat)abstract
- Simple, fast and accurate channel models can assist not only in a process of manufacturing of novel multi-core fibers, but also in a communication link design, providing a convenient way to investigate different properties of fibers that could be appealing for transmission. Models for coupled-core fibers are in a great demand since this type of the fiber provides advantages for data transmission, e.g. by reducing the effects of modal dispersion and fiber nonlinearity. In this work we present a comparative study of key features in a three coupled-core fiber (3CCF) for scalar and vector random coupling models. Supermodes and their group delays in an unperturbed 3CCF with polarization mode mixing are comprehensively analyzed for the first time. It is shown that birefringence does not impact significantly the group delay values but it may affect the mode mixing. The intensity impulse response and its RMS width were then investigated in a 3CCF with perturbations and compared for two types of models. The shape of the averaged intensity impulse response is found to be very similar for two models and retained for various input polarization states, while in the absence of averaging, the shape of the impulse response strongly depends on the input state of polarization. We show that the calculated RMS widths of the intensity impulse response agree well with theoretical values, as well as between scalar and vector cases.
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| 8. |
- Gao, Jitao, et al.
(författare)
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Active Mode-Selective Conversion Enabled by an Elliptical-Core Highly Nonlinear Few-Mode Fiber
- 2020
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Ingår i: Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS. - 1092-8081. ; 2020-May
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Konferensbidrag (refereegranskat)abstract
- We design an elliptical-core highly nonlinear few-mode fiber to achieve mode-selective conversion without parasitic wavelength conversion, using intermodal four-wave mixing. The proposed mode converter can be used in optical cross-connects over the C-band.
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| 9. |
- Gao, Jitao, et al.
(författare)
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Elliptical-Core Highly Nonlinear Few-Mode Fiber Based OXC for WDM-MDM Networks
- 2021
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1558-4542 .- 1077-260X. ; 27:2
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Tidskriftsartikel (refereegranskat)abstract
- In order to realize an optical cross-connect (OXC) converting wavelengths and spatial modes into one-dimensional switching ports, we propose an active mode selective conversion without parasitic wavelength conversion, based on the intermodal four-wave mixing (FWM) arising in a few-mode fiber (FMF). First, we design a dispersion-engineered elliptical-core highly nonlinear FMF (e-HNL-FMF) with a graded refractive index (RI) profile, which can independently guide 3 linearly polarized (LP) spatial modes. Meanwhile, a high doping concentration of germanium in the core leads to relatively high intermodal nonlinear coefficients of 3.23 (W·km)-1 between LP01 and LP11a modes and 3.14 (W·km)-1 between LP01 and LP11b modes. Next, we propose an e-HNL-FMF based OXC scheme for wavelength division multiplexing-mode division multiplexing (WDM-MDM) networks. After optimizing both the e-HNL-FMF length and pump power, we can realize either active mode selective conversion over the designated wavelength-band or three-wavelength to three-mode superchannel conversion for 100 Gbaud 16-quadratic-amplitude modulation (16-QAM) signals over the C-band. Due to excellent characteristics of the e-HNL-FMF, both cost and configuration complexity of the OXC can be reduced, showing great potentials for all-optical signal processing in the future WDM-MDM networks.
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| 10. |
- Gao, J. T., et al.
(författare)
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Design, fabrication, and characterization of a highly nonlinear few-mode fiber
- 2019
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Ingår i: Photonics Research. - 2327-9125. ; 7:11, s. 1354-1362
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Tidskriftsartikel (refereegranskat)abstract
- We present the design, fabrication, and characterization of a highly nonlinear few-mode fiber (HNL-FMF) with an intermodal nonlinear coefficient of 2.8 (W · km)−1, which to the best of our knowledge is the highest reported to date. The graded-index circular core fiber supports two mode groups (MGs) with six eigenmodes and is highly doped with germanium. This breaks the mode degeneracy within the higher-order MG, leading to different group velocities among corresponding eigenmodes. Thus, the HNL-FMF can support multiple intermodal four-wave mixing processes between the two MGs at the same time. In a proof-of-concept experiment, we demonstrate simultaneous intermodal wavelength conversions among three eigenmodes of the HNL-FMF over the C band.
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